Electrodes for cathode ray tubes with abutted ends meeting in a seam



M g N 9 0 Al 5 N N 3 H G O m w J M E d H T w i mF E April 30, 1968ELECTRODES FOR CATHODE RAY TUBES WITH ABUTTED PRIOR ART FIG] FIGS

FIG 3 m m N w E w N M H M w 5, Un A v 5w Y B 4. m Y El HAM. a w UHWMF 8\1 4 2 O 3 ATTORNEYS United States Patent 3,381,156 ELECTRODES FORCATHGDE RAY TUBES WITH ABUTTED ENDS MEETING IN A SEAM Jay H. Johnson,Owensboro, Ky., assignor, by mesne assiguments, to Kentucky Electronics,Inc., a corporation of Delaware Continuation-impart of application Ser.No. 221,601, Sept. 5, 1962. This application Dec. 30, 1965, Ser. No.517,679

1 Claim. (Cl. 313-32) ABSTRACT OF THE DISCLQSURE Improved structure forcathode ray tube electrodes is disclosed, wherein the electrode isformed from a fiat strip having edges rounded to eliminate burrs andbeing rolled around a mandrel to form a cylindrical body through whichthe electron beam passes, with ends abutting at a single seam generallyaligned along the beam path.

This application is a continuation-in-part of my copending applicationsSer. No. 221,600 and Ser. No. 221,601, filed Sept. 5, 1962, nowrespectively US. 'Patent No. 3,231,959 and abandoned.

This invention relates to the manufacture of parts for electron tubesand more particularly, to form-ing cylindrical electrodes for electronguns in cathode ray tubes.

'In the prior art, various methods were employed to fabricate annularfocusing anodes for electron guns which have been conventionally formedheretofore of seamless cylindrical stock. For example, one such methodof forming a cylindrical electrode such as the focusing anode is to forma cup from strip material on an eyelet machine by puncturing the stripbefore forming it in a progressive die-drawing operation. Next, theupper flange of the cup is trimmed to proper dimension and then thebottom of the cup is pierced to complete the annular ring. When theupper flange is trimmed, an outer lip is produced. The piercing of theend wall of the cup leaves a lip on the lower flange or opposite flangeof the anode. These irregularities tend to cause an out of roundnesswhich disturbs proper beam-shaping operation, for example, in the caseof a cylindrical focus anode, because they produce irregularities in theelectrostatic field surrounding the anode so that the field along theaxis of the cylinder is irregular. Furthermore, any sharp edges orprojections can cause corona since some of the electrodes are operatedat very high potential.

In addition to other defects of electrodes made by prior art methodswhich produce difliculty in meeting roundness and dimensionaltolerances, a simpler more efficient manufacturing technique isdesirable to reduce the possibility of rejects which increases when moreprocessing steps are introduced. Also a method 015 manufacturingelectrodes is desirable which does not involve the use of tools and diesin formation of critical tolerance dimensions such as roundness whichare subject to significant wear and deformation by abrasive actionagainst the parts when they are drawn or reshaped.

An object of the invention is to produce an electrode formed from asingle fiat metal blank formed into a cylinder and secured along a seamjoining the ends of the blank which extends in a direction generally thesame as the electron beam passing through the electrode.

Briefly, in accordance with aspects of this invention, I provide acylindrical electrode member with a seam extending along the directionof beam travel, which I find does not interfere with processing of thebeam, and thus obviates the disadvantages of the prior art methods of3,381,15b Patented Apr. 30, 1968 cylindrical electrode construction byforming a fiat blank the desired length, rolling the blank into acylinder and joining it at the ends by any convenient means such as byan interlocking arrangement of teeth and notches. When the blank isformed by rolling from a round wire or rod, the edges are roundedwithout further processing and undesirable lip structure on the edge ofthe annular ring produced by the prior art methods is eliminated.

These and various other objects and features of the invention are setforth in the detailed description of the invention with reference to theaccompanying drawing in which:

FIGURE 1 is a view in section of an annular anode produced by the abovedescribed prior art method;

FIGURE 2 is a view in elevation of a rod employed in this novel method;

FIGURE 3 is a blank formed from the rod of FIG- URE 2 and includinginterlock structure for joining the ends of the blank;

FIGURE 4 is a side view of an annular ring formed from a fiat blank suchas shown in FIGURE 3; and

FIGURES 5 through 8 show typical tools for forming the cylinder from aflat blank in a typical operational sequence.

Referring now to FIGURE 1, there is depicted a view in section of anannular ring 10 formed by the prior art method described above. Thisring 10 has an outer lip r12 on one edge and an inner lip 14 on theopposite edge. The lip '12 is formed when this edge is trimmed. The lip14 is formed 'when the end wall of the cup is pierced to define anannular ring. In each instance, the flange must be subsequently machinedto a very close tolerance. In addition, to the elimination of the lips'12 and 14, the internal and external diameters of focus anodes must beheld within close tolerances for the entire length of the ring and ithas been difiicult to maintain tolerances of 11001 on both internal andexternal diameters for the entire length of the ring under the priorart.

The novel focus ring according to this invention remains within anout-of-round tolerance of i001 both before and after firing (heattreating to remove impurities and gas from the ring prior to assembly ofthe cathode ray tube) even when fired in a bulk container. The prior artfocus rings are Work-hardened and subjected to stresses by the repeateddrawing and machining process. Unless they are individually stacked forfiring, the hardening and stresses tend to be relieved unevenly andcause the rings to become misshapen. They cannot, therefore, be fired assimply in bulk to meet the exacting roundness tolerances imposed uponelectrodes for electron guns.

Referring now to FIGURE 2, there is depicted a rod or wire 18 which isemployed in this novel method to produce an annular anode. The firs-tstep in this method is to roll and flatten a wire of proper diameter toproduce the desired round edges (28, 30 FIGURE 4) While obtaining thedesired fiat blank having a typical width such as .500 inch:.005 inchand thickness of .025 inch. After the desired width is obtained, notchesor grooves 20 preferably are cut in one end of the blank 22, Whileinterlock members or tongues 24 are cut on the opposite end of theblank. The blank 22 is now rolled over a suitable form, as laterdescribed to form annular ring 26 shown in FIG- URE 4, with theinterlocks 24 engaged in the notches 20 to secure the ends of the blankto each other thereby preventing any change of circumferential dimensionduring firing or use in an electron gun. The beam passes through thiselectrode in a general direction substantially the same as that of theseam.

Alternatively, the blank may be secured together by other structuralmethods such as abutting together noninterlocking tongues and groovesfor securing by spot welding together at the overlapped seams in thesame manner as shown at 38 in FIGURE 4. It is noted, however, that thepreferable construction of interlock members and notches prevents anymisshaping of the cylindrical tolerances either by expansion orcontraction due to heat expansion or other stresses over a more stablesurface area than reliance upon the spot weld position alone. Thus, ininterlocked structure of FIGURE 4 the spot weld serves to retain theinterlock members against radial changes of the end portions to preventany change in roundness during handling or assembly of the electrode anddoes not need to bear the greater circumferential stresses that may beimposed during heating of the electrode and its mounts in the tube orduring processing.

With this novel method, both internal and external diameters of theannular ring 26 of .625 inch inner diameter easily can be held withintolerances of plus and minus .001 inch, which tolerances are not readilyachieved by prior art methods. Further, because the blank 22 was rolledfrom a round wire 18, the edges 28 and 30 of the blank are round andthus, do not require Subsequent machining to eliminate irregularitieswhich might cause corona or out of roundness.

The flat electrode blank 22 is rolled over a cylindrical mandrel 40 bysequential movement of die members 41, 42, 43, and 44 in the mannerillustrated in FIGURES 5 through 8. Note in FIGURE 7 that die 42 isinserted before die 43 to permit the interlock members 24 to overlap thetop of the rolled cylindrical blank 26 of FIGURE 8, where they arepressed into fit by die members 44. Note that little abrasive actionagainst the blank 22 is introduced by the rolling action. Thus, thepresent method causes little wear of the dies or mandrel, asdistinguished over prior art methods of deep drawing or die-forming, andthere results a manufacturing process which produces electrodes heldmore closely within tolerances over long periods of time.

Therefore, this invention has provided a new electrode configuration forcylindrical electron gun electrodes which have a seam along the regionof abuttment of the ends of a single flat material blank wrapped intocylindrical form, together with methods of forming the electrode.

Contrary to possible exception, the seam produced by the abutting endsof the blank does not materially affect the action of the electrode uponthe beam, since there is no dilference of potential on opposite sides ofthe seam to serve as a focusing member, it is generally oriented alongthe cylinder in the direction of beam travel and there is very littlechange of radial dimension of the cylinder to effect the beam passingthrough the cylindrical electrode by changing the field configuration atthe position of the beam. Thus, it has been found that the seamedcylinder is an entirely satisfactory replacement for the prior art solidtubular equivalents.

Having therefore particularly described the advantages and nature of theinvention and its method of operation, those features believeddescriptive of the scope and spirit of the invention are set forth withparticularity in the appended claims.

What is claimed is:

1. An electrode for processing an electron beam in the electron gun of acathode ray tube comprising in combination, a thin fiat blank shapedinto a hollow electrode cylinder with a constant thickness wall and acylindrical inner electrode surface of constant diameter forestablishing a uniform inner electric field processing said beam throughan obstructed longitudinal inner beam path through the cylinder with twoends of the blank meeting in abuttment at a single seam generallyoriented longitudinally along the path of the beam through the innersurface, and structure securing the two ends of the blank togetheragainst any circumferential movement at the seam which might produce achange in the diameter of said internal electrode surface wherein theedges of the rectangular blank metal member are rounded.

References Cited UNITED STATES PATENTS 2,017,002 10/ 1935 Hodgson29--521 2,317,198 4/ 1943 Kasper 29521 2,540,621 2/ 1951 Johnson 31382.12,879,421 3 1959 Broadbent 31382 2,879,432 3/ 1959 Slivka 313-270 XFOREIGN PATENTS 1,119,057 12/ 1961 Germany.

668,707 3/ 1952 Great Britain.

JOHN W. HUCKERT, Primary Examiner.

A. 1. JAMES, Assistant Examiner.

